1. Field of the Invention
The present invention relates generally to a latch assembly, and in particular to a latch assembly having an adjustable backset.
2. The Prior Arts
“Backset” refers to the distance from the edge of the door to the center of the hole drilled for the lock. Most locks have backsets of 60 millimeters or 70 millimeters.
The user has to drill the hole on the door to install the lock, and the location of the hole is determined by the backset dimension of the door lock. If the door lock is out of order and needs to be replaced, the user needs to purchase a door lock with the same backset as the one to be replaced. Accordingly, the lock manufacturers have to produce latches in two different backsets to satisfy the needs of the users and the users have to purchase the appropriate locks according to the holes drilled on the doors.
However, for the manufacturers, manufacturing latches in two different backsets is hard to improve the production efficiency. For the users, it is likely to purchase the lock having a different backset.
In order to solve the problems mentioned above, a latch assembly of a lock having an adjustable backset has been proposed. The latch assembly includes an inner lock body, an outer lock body and a latch. The latch includes a casing, and a latch bolt and a latch rear section disposed in the casing. The latch bolt includes a bolt body and a fixed member connected with one end of the bolt body. The latch rear section holds the fixed member between an upper connecting member and a lower connecting member, on which pin holes are formed. As a pin is positioned at the first backset position, the latch assembly is adapted to the 60-millimeter backset distance. As a pin is positioned at the second backset position, the latch assembly is adapted to the 70-millimeter backset distance.
The backset of the latch assembly mentioned above is adjusted by regulating the position of the pin so that the fixed member can slide in a space inside the latch rear section. But this kind of latch assembly has many disadvantages, which are described as follows.
The backset of the latch is solely determined by the position of the pin. If the position of the pin is changed unintentionally, the backset of the latch is also changed unintentionally. Moreover, after the backset of the latch is adjusted, it is possible that the latch bolt is protruded out of the faceplate and can not be withdrawn back to the casing. Thus, the latch can not work normally.
Furthermore, because the length of the latch is determined by the relative position of the fixed member to the upper and lower connecting members. When the fixed member is projected out of the space between the upper connecting member and the lower connecting member, the strength of the latch is reduced.